Answer: 32
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Explanation:
There are two approaches.
Method 1)
20% of 40 = 0.20*40 = 8
Since 8 students are participating, this means 40-8 = 32 are not participating.
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Method 2)
20% are participating, so 100% - 20% = 80% are not participating
80% of 40 = 0.80*40 = 32
